The present invention is directed to a duplex strainer and, in particular, to a duplex strainer having an improved flow diverter mechanism.
Where a fluid, steam or gas flow is required in a given application, it is often necessary that the flow from an upstream source be cleaned or strained before use downstream from the source thereof. Where such flow is strained in a cleaning or straining mechanism, it is very often desirable for the flow to remain continuous. However, where the flow is strained, a strainer filter or basket will eventually become dirty and clogged. Thus, it becomes necessary to clean such basket or filter. In order to effect such cleaning, the flow of liquid, steam or gas would have to be stopped which, as aforenoted, is often undesirable and may be practically impossible in certain applications.
Duplex strainers have been developed in order to permit continuous straining and cleaning of a flow. Duplex strainers generally include two strainer chambers and some type of mechanism for diverting the flow from one chamber to the other to permit cleaning or repairing of one chamber while the other is in use. This permits the flow through the duplex strainer to remain continuous.
The prior art methods of diverting the flow from one strainer chamber to another have proven less than completely satisfactory. For example, one prior art technique utilizes two hand valves for the inlet and outlet ports of the two strainer chambers. The hand wheels are joined together by a chain link so that their operation remains synchronized. Such strainers require a two shaft drive and a precision threaded drive shaft design. Moreover, the drive shafts are in the path of flow thereby creating a potential for premature wear and possible malfunction. Multiple turns of the hand wheels are required to effect flow diversion. Accordingly, it would be desirable to provide an improved duplex strainer which overcomes the disadvantages of prior art designs.